Constant air velocity carburetor



May 8, 1951 L. J. SPRANGER 2,552,465

CONSTANT AIR VELOCITY CARBURETOR Filed July 9, 1949 2 sheetssheet 1 ZT 4TZ'l I..A J. SPRANGER CONSTANT A IR VELOCITY CARBURETOR 2 Sheets-Sheet 2Filed July 9, 1949 Patented May 8, 1951 UNITED STATES PATENT OFFICE 3Claims.

My invention relates to a carburetor embodying certain novel features bywhich to produce an effective mixture of fuel and air for operation ofan internal combustion engine. The present application is acontinuation-in-part of my application filed October l2, 1946, SerialNo. r102,972, now Patent No. 2,521,421, issued September 5, 1950.

The present carburetor includes in its construction means for increasingthe ratio of air to fuel with increase in the amount of the gaseousmixture, thereby conducing to increased economy in consumption. This isaccomplished by a mechanism which is simple and dependable in itsoperation. This objective of my invention, as `well as others which willhereinafter appear, may be attained by a construction of which asuggestive form is illustrated in the accompanying drawings, wherein-Figure 1 is a side elevation of the carburetor;

Fig. 2 is a top plan view thereof;

Fig. 3 is a Vertical section, taken on line 3--3 of Fig. 2;

Fig. 4 is a horizontal section, taken on line 4--4 of Fig. 3;

Fig. 5 is a detail in section, enlarged, taken on line 5 5 of Fig. 3;

Fig. 6 is a view similar to Fig. 3 in which the parts are shown ashaving been operated to another position;

Fig. '7 is a view in perspective of the choke plunger; and

Fig. 8 is a perspective view of the feed tube leading from the fuelchamber.

The body of the present carburetor is formed to provide` an air chamberA in line with a mixing chamber M to one side cf which is a fuel chamberF. The walls defining these three chambers are suitably joined toprovide a unitary structure. Leading into the fuel chamber is a fuelpipe IB, and opening into the air chamber is an air inlet Il. The bottomof the mixing chamber is open for operative connection with the intakemanifold (not shown) of an internal combustion engine.

The iiow of liquid fuel into the fuel chamber is controlled by a valvein the pipe lil, operated by a float l5 which is pivotally supportedupon a bar I6 to swing up or down in response to fluctuations in thelevel of the fuel Within the chamber. By such a conventional means it ispossible to keep a substantially constant level of fuel within the fuelchamber at all times.

A pair of tubes 2U and 2l are extended obliquely downwardly into theVfuel chamber from its wall 22 which is proximate to the mixing chamber.Each of these tubes may be secured by ascrew threaded connection withincylindrical passages which extend through the wall 22 and the adjacentwall 23 of the mixing chamber into communication with the latter (seeFig. 5).

The tube 2E is closed at the bottom by a plug 25 against which is thrustthe lower end of a coiled spring 25 whose upper end resiliently supportsa plunger 2l having at its top a head in the form of a truncated cone 28seating within an axial opening which extends through'an end wall29 atthe top end of the tube. The top end of the truncated cone head projectsslightly into the mixing chamber when the plunger is in its uppermostposition, the opening around the cone then being closed. This plunger,together with its cooperatingl seat, forms a choke valve which will befurther explained hereinafter. As shown, the plunger body is polygonalin cross section so that spaces along its sides `will remain to providea passageway between the plunger and its surrounding tube. Ports 30extend through the tube wall near its lower end to permit fuel to entertherethrough into the tube. At a point opposite the lower end of thetube, the bottom wall 8| of the fuel chamber is apertured to receive aclosure plug 32 which is maintained in place by a screw threadedconnection. When this plug is removed, the tube 2li may be passedendwise therethrough. End slots 33 in the tube permit application of ascrew driver whereby to rotate the tube either way for purposes ofassembly or` disassembly with the mixing chamber wall 23.

The second tube 2| is also closed at the bottom by an end wall 35adapted to receive the thrust of a coiled spring 36 which extends withinan inner tube 3l, open at the bottom, but closed at the top by an endwall 3B through `which is a small axial opening 39 lying within a crossgroove 40. This inner tube is provided with a plurality of, small ports4I in stepped formation, close to its upper end, and in response totension of the spring 36 the inner tube is urged upwardly to projectinto the mixing chamber, thereby to expose more or less of its side wallports 4l :according to the distance to which the tube is projectedaxially of itself. Near the bottom of the outer tube 2|, I providesidewall ports 42 through which liquid fuel may enter to risetherewithin. To facilitate assembly of the tube 2! into operativeposition, a second closure plug 43, the same as the plug 32, may beremovably fitted;` in the fuelchamber. bottom Wall 3l. The wall passageswherein the tubes 20 and\2| are mounted open out upon a beveled seat 45which is extended circularly within the mixing chamber M. A valve memberin the form of a beveled disk 46 is adapted to be moved toward and fromthis seat and in all of its positions to be engaged by the upper end 38ofthe inner tube 31. In the lower part of its movement range this diskwill also remain in engagement with the end of the cone 28 that isprojected from the plunger 21. This valve disk is carried by a stem 41whose lower end is slidably supported in a tubular guide 48 which V'by apair of webs 49 is maintained lxedly in a centerl position near thebottom end of the mixing chamber. A spring 58 which is coiled around thestem exerts opposing thrusts upon the guide and disk whereby to normallyhold the valve in an up position off of its seat 45 (see Fig. 6).. Ifdesired, a valved connection 5l may be entered into the mixingchamber'to supply water thereto in a controlled amount.

The upper end of the stem is slidingly conned within a tube 54 whosebottom end is laterally anged to provide a second valve disk 55. Thisdisk 55 which occupies an upper position relative V-to the first valvedisk 46 is'beveled on its under face for cooperation with a beveled seat56 which is extended circularly inwardly from' the surrounding walls toprovide a partial separation and Vand the stem is also provided, thistaking the form of a cross pin 51 which is carriedY by one forengagement within a vertically disposed slot 58 in the other.

The tube 54 extends from the upper valve disk upwardly within acylindrical guide wall 68 that depends into the air chamber A from a topwall 6 I. This guide wall also rises above the top wall to furnish aswiveled mounting for the cupped end 65 of a lever 66 which' is adaptedto be operated by a link connection 61 from a suitable control (notshown). As by a set screw 68 entered through the cup Wall 65 to bearwith pressure against the tube 54 IY provide for transmitting rotarymotion thereto whenever the lever 66 is operated. A screw 16 which issecured to the tube 54 extends laterally thereof to present its headwithin a spiral cam slot 1| that is formed in the guide wall 6U (seeFig. 6), so as to cause the tube 54 to be raised or lowered with eachoperation of the lever 66. By some such means as this, the upper valvedisk 55'is moved toward and from its seat 56, the lower valve disk 46being also moved in unison therewith. The point of minimum clearancebetween the valve disk` 55 and its seat 56 may be determined by a stop65 that is adjustably'mounted on the top wall 5l to engage the lever 66when operated to its limit in a clockwise direction as viewed in Fig. 2.

4 l l disk 46 against the seat, the slip movement at the pin and slotconnection 51 and 58 permitting this disk to reach this position evenwhen the upper valve disk 55 is slightly separated from its seat.

In operation, when the leverv 66 is moved, the stem 41 will be lifted toraise the valve disk 46 off of its seat. YIn this movement the plungervhead 2,8 is permitted to advance outwardly whereby tov close theopening through the port 29. Concurrently the inner tube 31 advancesoutwardly to expose additional ports 4I through which liquid fuel isdrawn into the mixing chamber. VAir enteringthrough the opening Ildescends into the mixing chamber since the valve disk 55 is movedfurther away from its seat when the lever 65 is operated. Under theseconditions, a gaseous mixture is produced which, when admitted into anassociated internal combustion engine, will eiectively support continuedoperation thereof.

Manifestly when the valve disk 45 is moved away from or toward its seat,the amount of fuel admitted into the mixing chamber is increased ordecreased, respectively; at the same time the area of the opening aroundthis valve into the passageway leading to the internal combustion engineis varied, being either increased or decreased as this valve moves awayfrom or toward its seat. In these operations there is a constant inflowof air through the port l l, passing around the valve disk 55,*to enterinto the mixing chamber. This iniiow varies with the amount of fueladmitted into the mixing chamber since the two valve disks 55 and 46operate in unison in theirv movements toward and from their respectiveseats. There is accordingly maintained through the carbureter an airmovement of constant velocity.

Vthrough the port 29 into the mixing chamber while inflow of air isgreatly reduced through maintaining the valve disk 55 in a nearly closedposition. A very richY mixture, such'as Yis required under cold startingconditions, may accordingly be produced by the manipulation justdescribed.

I claim: Y 1. A carburetor in which is combined a fuel chamber and amixing chamber, the latter hav- To operate the lower valve'disk 46 thereis Y slidably positioned through the upper end 12 of the tube 54 andaxially thereof a pin 15 whose lower end is rested upon the top end ofthe stem At its top end this pin is engaged at 16 by one arm of a bellcrank lever 11 .which is pivoted at 18 to the upper end of a bracket 19thatY upstands from the top wall 6l of the air chamber; To the other armof the bell crank is pivoted at 80 an operating rod 8l leading to asuitable control (not shown). By the -means justdescribed, I provide foroperation of the choke valve through movement imparted to the stem 41which, when downwardly moved, will advance the lower valve ing a seatwith a valve movable toward and from the same, an air chamber incommunication with the mixing chamber and partially separated therefromby an annular seat, a valve in the air,

, ably supported on said stem and to the lowerV end of which the valvein the air chamber is secured,

a limited slip connection between Vthe stem and the valve in the airchamber providing for move-` stem to concurrently operate said valves;and` separate means for moving the valve in the miX-' ing chamber aslight distance toward its seat independently of movement of the valvein the air chamber.

2. A carburetor in which is combined a fuel chamber and a mixingchamber, the latter having a seat with a valve movable toward and fromthe same, an air chamber in communication with the mixing chamber andpartially separated therefrom by an annular seat, a valve in the airchamber movable toward and from its seat, a stem slidably supported formovement longitudinally and which carries the valve in the mixingchamber, a spring biasing the valve in the mixing chamber away from itsseat, a tube slidably supported on said stem and on the lower end ofwhich is secured the valve in the air chamber, a limited slip connectionbetween the stem and the valve in the air chamber providing for movementof the valve in the mixing chamber a slight distance independently ofthe movement of the valve in the air chamber, means for moving said stemto concurrently operate said valves, and separate means for moving thevalve in the mixing chamber a slight distance toward its seatindependently of movement of the valve in the air chamber, said lastmentioned means including a rod slidably mounted on said tube to extendlongitudinally within the same from one end thereof to engage the outerend of said stem.

3. A carburetor in which is combined a fuel chamber and a mixingchamber, the latter having a seat with a valve movable toward and fromthe same, an air chamber in communication with the mixing chamber andpartially separated therefrom by an annular seat, a Valve in the airchamber movable toward and from its seat, a

longitudinally movable stem which carries the valve in the mixingchamber, a spring biasing the valve in the mixing chamber away from itsseat, a tube slidably supported on said stem and on the lower end ofwhich is secured the valve in the air chamber, a limited slip connectionbetween the stem and the Valve in the air chamber providing for movementof the valve in the mixing chamber a slight distance independently ofmovement of the valve in the air chamber, a stationary sleeve member inwhich said tube is slidably confined, means for moving said stem toconcurrently operate said valves including a cam slot in said stationarysleeve member, a pin projecting laterally from said tube engaging saidcam slot, and means for imparting rotary movement to said tube, andseparate means for moving the valve in the mixing chamber a slightdistance toward its seat independently of movement of the valve in theair chamber, said last mentioned means including a rod slidably mountedon said tube to extend longitudinally Within the same from one endthereof to engage the outer end of said stem.

LEONARD J. SPRANGER.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,020,198 Hamill Mar. 12, 19121,235,165 Sessions July 31, 1917 1,239,442 Anderson Sept. 11, 1917

